Known for their bright colors and prolific breeding habits, swordtails (Xiphophorus helleri) are popular beginner fish among freshwater hobbyists. They’re also easy to identify by the long, swordlike tail extensions that mature males develop. If you’re looking for a hardy, friendly fish, the swordtail offers a wide array of color options to choose from.
Species Snapshot
· Species Name: Xiphophorus helleri
· Common Names: Swordtail
· Size: Up to 6 inches
· Lifespan: 3-5 years
· Native Distribution: Mexico and Central America
Though they are relatively hardy, swordtails have certain preferences when it comes to their habitat. Here’s what you need to know about these peaceful community fish and how to care for them properly.
Anatomy and Appearance
Swordtails have been a mainstay in the aquarium trade for quite some time, so they’re found in a wide array of color variants by now. The species’ natural coloration is green, but swordtails come in a range of bright colors, ranging from the golden yellow of Sanke Koi to the bright red of the Lyretail Swordtail. You’ll also find them with different fin shapes, including hi-fin and lyretail varieties.
One of several popular freshwater live-bearing species, swordtails bear a strong resemblance to the platy (Xiphophorus variatus). Platies are, in fact, closely related to swordtails but don’t bear the iconic swordlike tail extensions.
On average, the swordtail reaches up to 5 inches in length at maturity. Males may appear larger, given the added length of their tails. Swordtails have elongated, laterally compressed bodies with a slight curve along their backs—similar to other livebearers like platies and guppies.
Female swordtails (in addition to the absence of the sword) are often thicker in body than males and may have a rounded edge to their tails.
Ideal Aquarium Setup
What makes swordtails so popular is their adaptability. These fish are relatively hardy, given their long history of captive breeding, and generally do well in most freshwater community tank setups. The key is to keep their breeding habits in mind and choose a tank large enough to accommodate an expanding population (or make plans to keep the population under control).
Tank Size
While swordtails aren’t a schooling species, they do tend to prefer being kept in groups of 4-5 of their own kind. For a small group of swordtails, the minimum recommended tank size is 10 gallons. Plan to provide a larger tank if you’re going to keep your swordtails with other community fish—especially other livebearers that can be expected to breed regularly.
Water Parameters
Swordtails are adaptable to both freshwater and brackish habitats but tend to prefer swift-moving, heavily planted tank environments. Live plants provide shelter for newly born fry, and adult fish may snack on plants to some degree, though they typically don’t bother healthy plants.
In terms of water chemistry, swordtails are best kept in pH-neutral to slightly alkaline water with a pH range of 7.0 to 8.5. They can tolerate a water hardness range of 12-30 dGH and prefer cool to warm temperatures from 64°F to 82°F. Strong biological filtration is essential for a growing swordtail population, but these fish will also appreciate a filter that produces a moderate degree of flow.
Test your tank water weekly to ensure your parameters are within the proper ranges. Small weekly water changes are recommended to keep water quality high, with larger monthly water changes if needed to remove excess ammonia and nitrite.
Tank Décor
As previously mentioned, planted tanks offer the ideal setup for swordtails. Having a tank full of thriving plants will also help keep oxygen levels in the water high and may help with nutrient balance as well. If you plan to breed your swordtails, consider growing some carpet plants for the fry to hide in—floating plants with long roots may work as well.
In terms of other décor, go for natural elements like driftwood and rockwork. Anubias anchored to driftwood makes a hardy decoration for a swordtail tank. It will also provide some additional surface area to grow algae and biofilm for newly born fry to feed on.
Diet and Feeding
Swordtails are omnivores, so they’ll accept a wide range of fish food: commercial, live, and frozen foods. The thing to keep in mind with swordtails is that they tend to occupy the middle to upper levels of the tank, so floating or slowly sinking foods are best. It’s also important to choose food that’s small enough to fit in your swordtails’ mouths without much effort.
Consider offering your swordtails a staple diet of commercial flakes or micro-pellets formulated for tropical fish. Your swordtails will appreciate supplementation with live, frozen, and freeze-dried foods several times a week. Good options include brine shrimp, daphnia, and bloodworms. Just stick to small feedings to prevent your fish from overeating.
Temperament and Tank Mates
Swordtails are the ideal community species. They’re non-aggressive and grow big enough to hold their own against similarly sized fish. It’s best to avoid keeping them with very large or aggressive fish, however, especially carnivorous species that might consider them prey. Keep in mind that any newly born swordtail fry will likely become prey as well, unless you take measures to protect them.
Some of the best tankmates for swordtails include small tetras and bottom-dwellers like corydoras, catfish, and kuhli loaches. Other livebearers are a good fit as well, but be prepared to deal with a lot of fry if you keep multiple live-bearing species together.
Breeding Swordtails
If you have an interest in breeding aquarium fish, swordtails are a great choice. It’s easy to tell the difference between the sexes, and these fish breed readily with little to no intervention. Keep in mind, however, that male swordfish don’t develop the extension on their tails until they reach sexual maturity (around 3 months of age).
Swordtails can produce as many as 50 fry per spawning, so it’s best to separate the males from females unless you’re prepared to raise the fry. The other option is to make no intervention and let the fry become a food source for the other fish in your tank. Over time, your swordtails may start to produce fewer fry (or they might experience a higher death rate) due to inbreeding, unless you introduce new stock to the tank.
Wrapping up
Swordtail care is pretty straightforward once you understand their needs: a comfortable, well-planted tank, clean and pH-neutral water, and a varied diet all help keep these fish healthy and active.
Hardy, social, and easy to breed, swordtails are a wonderful choice for both beginners and experienced hobbyists. At Shrimpy Business, we’re passionate about helping aquarists create the best environments for their fish.
Contact us today to learn how to get started with swordtails and create the perfect environment for them to thrive!